Patent GB-950313-A (GB)
Title: Xerographic reproduction apparatus
IPC: G03G15/041
Filed: 1960-01-12
Abstract: 950,313. Xerographic projection printing apparatus. RANK-XEROX Ltd. (Haloid Co.). Jan.12, 1960, No. 1123/60. Headings G2A and G2H. Apparatus for optically projecting images from moving image-bearing member on to a moving receiving surface includes means providing a range of selectable magnification ratios and means for adjusting the rate of transport of the image-bearing member so that this is in the same ratio to the rate of transport of the imagebearing member as the operative magnification ratio. As shown, a film to be projected is arranged between supply and take-up spools 59, 78 over rollers 64, 65 driving roller 75 and roller 79 on a removable support 56 which is located by rods 53, 54 on a wall 1 and bolts 57, 58 engaging studs on that wall, a bolt 55 adjusting the position of the support for film centring. To select a desired magnification a turret 92 rotatably mounted on the wall, and bearing objective and film gate support assemblies is freed from its locking pawl 123 and rotated until a cam on the turret shaft has moved a mask 139 to reveal in window 140 the appropriate one of a set of magnification ratios on a plate 141 fixed to the frame of the apparatus. Knob 143 is then rotated and via bevel gears 151, 152 and an internal thread on gear 152 screw shaft 152 is rotated to move the wall 1 vertically along posts 26, 27 and so alter the projection distance until the chosen magnification value is aligned in the window 140 with the index 142 when the shaft 152 is locked by means of knob 164. The barrel 117 of the chosen objective is then rotated relative to a fixed mark 118 to focus for the chosen magnification shown on a scale on the barrel and barrel 119 is then rotated to bring a marking U or D against the mark 118 according as to whether the film is arranged with its imagebearing layer up or down. The light source is then positioned to illuminate the projection film gate by adjustment of the ring 30 which moves it axially and screw controlled slides 31, 37 which position it vertically and horizontally. A blower 41 is provided for cooling the lamp. Handle 174 is then slidably adjusted thus selecting the appropriate speed for the film driving motor 173 and moving a mask 177 to uncover the appropriate magnification ratio scale 172 and gear lever 178 is adjusted to bring a mark 196 against the previously selected magnification value, so selecting a gear ratio to impart the appropriate speed to the shaft 229 which drives the film driving roller 75. A light tunnel 254 extends from the projector housing and terminates in an adjustable slit 262 whereby the exposure of a continuously rotating fixed speed xerographic drum is controlled, the slit adjustment means being calibrated in exposure times. About the drum are disposed in succession in well-known manner a corona charging station, the slit exposure gate, cascade developer, electrostatic powder image transfer means whereby the powder image is transferred to a paper or other web and subsequently fused thereto, contrarotating brushes for removing residual powder and a lamp for discharging any image charge before uniformly re-charging the drum.